苹果黑点病不同症状类型致病菌及侵染条件研究

摘要

为了明确黑点病的诱因与发病条件,将套袋苹果的黑点病斑划分为黑斑型、褐变型、黑点型和内变型4种类型。黑斑型病斑中, Alternaria属的病菌分离频率最高,占89%；褐变型病斑中, Acremonium和Alternaria分离频率较高,占80%以上；黑点型病斑中,Trichothecium和Alternaria的分离频率高,占75%以上。其中,3株分离频率较高的真菌分别为A. tenuissima、A. sclerotigenum和T. roseum。3株病菌中离,T. roseum致病力最强,从离体果实的伤口侵染后形成大型褐色病斑,病菌侵染与扩展的最适温度分别为26.8,22.5℃；A. tenuissima致病力稍弱,从伤口侵染后形成的病斑稍小,颜色为深褐至黑色,病菌侵染与扩展的最适温度分别为29.4,28.5℃；A. sclerotigenum的侵染率很高,对温度不敏感,从伤口侵染后也能导致果肉组织褐色坏死,形成红褐色病斑。3种病菌的分生孢子均不能侵染成熟无伤果实。用3种真菌分生孢子接种的套袋果实,T. roseum接种果实发病最重,A. tenuissima接种的果实发病率稍低,用A. sclerotigenum接种的果实几乎没有发病。黑点病菌属于机会致病菌,遇适宜条件才能侵染致病。%Four types lesions of black tissues type,brown type,black spot type and hardening type were divided in order to determine reasons and infection conditions of black spot disease. The isolation percentage of Alternaria spp. was 89% from black tissues type. The isolation percentage of Trichothecium and Alternaria were 75%,and iso-lation percentage of A. tenuissima,A. sclerotigenum and T. roseum were the highest. Among them,T. roseum was the most pathogenic pathogen which led to large brown lesion on ripe fruit when infected from wounds. The optimum temperatures for infection by conidia of T. roseum and lesion expansion were 26. 8,22. 5℃ respectively. A. tenuissi-ma caused large dark or brown lesions on ripe apple fruit when infected from wounds. The optimum temperatures for infection by conidia of A. tenuissima and lesion expansion were 29. 4,28. 5℃ respectively. A. sclerotigenum owned the highest infection ratio from wounds of mature apple fruit and let to small red-brown lesions on the fruit. The pathogen can fit a wide range of temperature when infection from wounded apple fruit. Conidia of three pathogens could not infected healthy apple. The inoculation with conidia of T. roseum caused significant more lesions on the bagged fruits than the oth-er two pathogens,then the A. tenuissima,and A. sclerotigenum almost did not cause diseased lesions. Pathogens of black spot disease were chance pathogens,and caused disease when met suitable conditions.